Extraction solvent control for reducing stable emulsions

ABSTRACT

Disclosed herein are methods for recovering diphosphite-containing compounds from mixtures comprising organic mononitriles and organic dinitriles, using liquid-liquid extraction. Also disclosed are treatments to enhance extractability of the diphosphite-containing compounds.

RELATED APPLICATION

This application claims benefit to Provisional Application No.61/578,535 filed on Dec. 21, 2011 which is herein incorporated byreference in its entirety.

FIELD OF THE INVENTION

The invention relates to recovery of catalyst and ligand from ahydrocyanation reaction product mixture comprising organic dinitrilesusing liquid-liquid extraction.

BACKGROUND OF THE INVENTION

It is well known in the art that complexes of nickel withphosphorous-containing ligands are useful as catalysts in hydrocyanationreactions. Such nickel complexes using monodentate phosphites are knownto catalyze hydrocyanation of butadiene to produce a mixture ofpentenenitriles. These catalysts are also useful in the subsequenthydrocyanation of pentenenitriles to produce adiponitrile, an importantintermediate in the production of nylon. It is further known thatbidentate phosphite and phosphinite ligands can be used to formnickel-based catalysts to perform such hydrocyanation reactions.

U.S. Pat. No. 3,773,809 describes a process for the recovery of Nicomplexes of organic phosphites from a product fluid containing organicnitriles produced by hydrocyanating an ethylenically unsaturated organicmononitrile such as 3-pentenenitrile through extraction of the productfluid with a paraffin or cycloparaffin hydrocarbon solvent. Similarly,U.S. Pat. No. 6,936,171 to Jackson and McKinney discloses a process forrecovering diphosphite-containing compounds from streams containingdinitriles.

U.S. Pat. No. 4,339,395 describes the formation of an interfacial raglayer during extended periods of continuous extraction of certainphosphite ligands. The '395 patent notes that the interfacial raghinders, if not halts, the phase separation. Because the process isoperated continuously, the rag must be removed continuously from theinterface as it accumulates to avoid interrupting operation. To solvethis problem for the disclosed components, the '395 patent discloses theaddition of minor amounts of substantially water-free ammonia.

SUMMARY OF THE INVENTION

This process recovers diphosphite-containing compounds from a mixturecomprising diphosphite-containing compounds, organic mononitriles andorganic dinitriles.

Disclosed is a process for recovering diphosphite-containing compoundsfrom a feed mixture comprising diphosphite-containing compounds, organicmononitriles, organic dinitriles and a Lewis acid in a multistagecountercurrent liquid-liquid extractor with extraction solventcomprising aliphatic hydrocarbon, cycloaliphatic hydrocarbon or amixture of aliphatic and cycloaliphatic hydrocarbon. The processcomprises:

a) flowing the feed mixture to the first stage of the multistagecountercurrent liquid-liquid extractor; andb) contacting the feed mixture with extraction solvent in the multistagecountercurrent liquid-liquid extractor;

wherein the first stage of the multistage countercurrent liquid-liquidextractor comprises a mixing section and a settling section, wherein alight phase separates from a heavy phase in the settling section,wherein a Lewis base is added to the mixing section of the first stageof the multistage countercurrent liquid-liquid extractor, wherein thelight phase comprises extraction solvent and extracteddiphosphite-containing compounds, wherein the heavy phase comprisesorganic mononitriles, organic dinitriles and a complex of said Lewisacid and said Lewis base, wherein at least a portion of the light phaseis withdrawn from the settling section and treated to recoverdiphosphite-containing compounds extracted into the light phase, whereinat least a portion of the heavy phase is passed to the second stage ofthe multistage countercurrent liquid-liquid extractor.

The mixing sections of the stages of the multistage counter currentliquid-liquid extractor form an intimate mixture of unseparated lightand heavy phase. This intimate mixture comprises an emulsion phase. Theemulsion phase may or may not comprise particulate solid material. Thisemulsion phase separates into a light phase and a heavy phase in thesettling sections of the stages, including the first stage. Accordingly,the settling sections of the stages will contain at least some emulsionphase located between the upper light phase and the lower heavy phase.This emulsion phase tends to reduce in size over time. However, in someinstances settling takes longer than desired or the emulsion phase neverfully separates into a light phase and a heavy phase. This separationproblem may be particularly troublesome in the first stage of amultistage countercurrent liquid-liquid extractor.

Addition of Lewis base to the mixing section of the first stage has beenfound to result in enhanced settling of the emulsion phase. For example,this addition may result in the reduction of the size of the emulsionphase in the settling section, wherein the size of the emulsion phase isbased upon the size of the emulsion phase in the absence of addition ofLewis base. Enhanced settling in the settling section may also bemeasured as an increased rate of settling, based upon the rate ofsettling in the absence of addition of Lewis base.

Another problem, which may be solved by addition of Lewis base isformation of rag and build-up of a rag layer the settling section. Ragformation is discussed in U.S. Pat. No. 4,339,395 and U.S. Pat. No.7,935,229. Rag comprises particulate solid material, and may beconsidered to be a form of an emulsion phase, which is particularlystable in the sense that it does not dissipate in a practical amount oftime for conducting an extraction process. Rag may form in the mixingsection or the settling section of an extraction stage, particularly thefirst stage of a multistage countercurrent liquid-liquid extractor. Inthe settling section, the rag forms a layer between the heavy phase andthe light phase. The formation of a rag layer in the settling sectioninhibits proper settling of the heavy phase and the light phase. Theformation of a rag layer may also inhibit the extraction ofdiphosphite-containing compounds from the heavy phase into the lightphase. In a worst case scenario, rag can build up to extent ofcompletely filling a separation section, necessitating shut down of theextraction process to clean out the settling section. It has been foundthat addition of Lewis base to the mixing section may reduce oreliminate the size of a rag layer or reduce its rate of formation, basedupon the size and rate of formation of the rag layer in the absence ofaddition of Lewis base.

Accordingly, addition of Lewis base to the mixing section of the firststage of a multistage countercurrent extractor may achieve at least oneof the following results: (a) a reduction in the size of an emulsionphase in the settling section, based upon the size of the emulsion phasein the absence of addition of Lewis base; (b) an increase in the rate ofsettling in the settling section, based upon the rate of settling in theabsence of addition of Lewis base; (c) an increase in the amount ofdiphosphite-containing compounds in the light phase, based upon the uponthe amount of diphosphite-containing compounds in the light phase in theabsence of addition of Lewis base; (d) a partial or total reduction inthe size of a rag layer in the settling section, based upon the size ofa rag layer in the settling section in the absence of addition of Lewisbase; and (e) reduction in the rate of formation of a rag layer in thesettling section, based upon the rate of formation of a rag layer in thesettling section in the absence of addition of Lewis base.

In one embodiment, Lewis base is cofed to the mixing section along withthe feed mixture comprising diphosphite-containing compounds, organicmononitriles, organic dinitriles and Lewis acid. In another embodiment,Lewis base is separately fed to the mixing section apart from the feedmixture comprising diphosphite-containing compounds, organicmononitriles, organic dinitriles and Lewis acid and the extractionsolvent feed.

A particular example of a Lewis acid, which may be present in the feedto the extractor, is ZnCl₂.

The extraction solvent feed from the second stage may comprise at least1000 ppm, for example, from 2000 to 5000 ppm, of diphosphite-containingcompounds. The extraction solvent feed from the second stage maycomprise at least 10 ppm, for example, from 20 to 200 ppm, of nickel.

The diphosphite-containing compound may be a diphosphite ligand selectedfrom the group consisting of:

and

wherein in I, II and III, R¹ is phenyl, unsubstituted or substitutedwith one or more C₁ to C₁₂ alkyl or C₁ to C₁₂ alkoxy groups; ornaphthyl, unsubstituted or substituted with one or more C₁ to C₁₂ alkylor C₁ to C₁₂ alkoxy groups; and wherein Z and Z¹ are independentlyselected from the group consisting of structural formulae IV, V, VI,VII, and VIII:

and wherein

R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, and R⁹ are independently selected from thegroup consisting of H, C₁ to C₁₂ alkyl, and C₁ to C₁₂ alkoxy;

X is O, S, or CH(R¹⁰);

R¹⁰ is H or C₁ to C₁₂ alkyl;

and wherein

R¹¹ and R¹² are independently selected from the group consisting of H,C₁ to C₁₂ alkyl, and C₁ to C₁₂ alkoxy and CO₂R¹³,

R¹³ is C₁ to C₁₂ alkyl, or C₆ to C₁₀ aryl unsubstituted or substitutedwith C₁ to C₄ alkyl;

Y is O, S, or CH(R¹⁴);

R¹⁴ is H or C₁ to C₁₂ alkyl;

wherein

R¹⁵ is selected from the group consisting of H, C₁ to C₁₂ alkyl, and C₁to C₁₂ alkoxy and CO₂R¹⁶,

R¹⁶ is C₁ to C₁₂ alkyl, or C₆ to C₁₀ aryl, unsubstituted or substitutedwith C₁ to C₄ alkyl,

and wherein

for structural formulae I through VIII, the C₁ to C₁₂ alkyl, and C₁ toC₁₂ alkoxy groups may be straight chain or branched.

At least a portion of the diphosphite ligand may be complexed with zerovalent Ni.

At least one stage of the extraction may be carried out above 40° C.

The Lewis base may be a monodentate triarylphosphite, wherein the arylgroups are unsubstituted or substituted with alkyl groups having 1 to 12carbon atoms, and wherein the aryl groups may be interconnected.

The Lewis base may optionally be selected from the group consisting of:

a) anhydrous ammonia, pyridine, alkylamine, dialkylamine, trialkylaminewherein the alkyl groups have 1 to 12 carbon atoms; andb) polyamine.

If the Lewis base is a polyamine, the polyamine may comprise at leastone selected from hexamethylene diamine, and dimers and trimers ofhexamethylene diamine, for example, bis-hexamethylene triamine.

The Lewis base may optionally comprise a basic ion exchange resin, forexample, Amberlyst 21® resin.

One example of a suitable cyclic alkane extraction solvent iscyclohexane.

At least a portion of the process may be carried out in an extractioncolumn or a mixer-settler.

The feed mixture may be an effluent stream from a hydrocyanationprocess, for example, a process for hydrocyanating 3-pentenenitrile, aprocess for the single hydrocyanation of 1,3-butadiene topentenenitriles or a process for the double hydrocyanation of1,3-butadiene to adiponitrile.

The first stage of the multistage countercurrent liquid-liquid extractormay take place in an extraction column. The entire column may beconsidered to be a settling section comprising a mixing section betweena heavy phase collection section and a light phase collection section.Heavy phase may be recycled to the mixing section of the extractioncolumn.

The first stage of the multistage countercurrent liquid-liquid extractormay takes place in an mixer-settler. The mixer-settler may comprise asettling section which is separate from the mixing section. Recycledheavy stream may be recycled upstream from the point of withdraw of therecycled heavy stream.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the flow of fluids through a multistagecountercurrent liquid-liquid extractor.

FIG. 2 is a diagram showing a mixing section and a settling section of astage of a multistage countercurrent liquid-liquid extractor.

FIG. 3 is a diagram showing an extraction column.

FIG. 4 is a diagram showing a mixing/settling apparatus having threechambers in the settling section.

DETAILED DESCRIPTION OF THE INVENTION

The processes of the present invention involve methods for recoveringdiphosphite-containing compounds from a mixture comprisingdiphosphite-containing compounds and organic dinitriles, usingliquid-liquid extraction.

FIG. 1 is a diagram of a multistage countercurrent liquid-liquidextractor. Lines in FIG. 1 represent flow of materials, rather than anyparticular type of equipment, such as pipes. Similarly, squares in thisdiagram represent stages or sections for mixing and settling, ratherthan any particular type of equipment.

Three stages are depicted in FIG. 1. The first stage is depicted bymixing and settling section 1. The second stage is depicted by mixingand settling section 2. The final stage is depicted by mixing andsettling section 3. Gap 30 represents a space where additional stagesmay be inserted. For example, one or more, for example, from one tofour, mixing and settling sections may be inserted in gap 30 betweenmixing and settling section 2 and mixing and settling section 3.

In FIG. 1, a fresh extraction solvent feed, for example, cyclohexane, isintroduced into the multistage countercurrent extractor via line 10. Theextraction solvent or light phase exiting from mixing settling section 3passes through line 12 to the next stage of the multistage extractor. Ina multistage countercurrent liquid-liquid extractor having three stages,extraction solvent in line 12 would pass directly into stage 2 via line14. Extraction solvent from stage 2 passes through line 16 to stage 1.The extraction solvent comprising extracted diphosphite-containingcompounds passes out of the stage 1 mixing and settling section throughline 18.

A feed comprising diphosphite-containing compounds is fed into the stage1 mixer and settler via line 20. The feed further comprises a mixturecomprising organic mononitriles and dinitriles, which is immiscible withthe extraction solvent. The feed further comprises a Lewis acid. Instage 1, a portion of the diphosphite-containing compounds is extractedinto the extraction solvent which exits stage 1 via line 18. Theimmiscible dinitrile and mononitrile mixture or the heavy phase isremoved from the stage 1 mixing and settling section by line 22 and ispassed into the stage 2 mixing and settling section. A portion of thediphosphite-containing compounds is extracted into the light phase inthe stage 2 mixing and settling section. The heavy phase exits the stage2 mixing and settling section by line 24. Similarly, if there areadditional stages in gap 30 shown in FIG. 1, extraction ofdiphosphite-containing compounds will take place in such intermediatestages in a similar manner to that taking place in stage 2.

After the heavy phase passes through the first stage and anyintermediate stages, it passes through the final stage mixing andsettling section 3. In particular, the heavy phase is introduced intomixing and setting section 3 through line 26. After passing through thefinal stage mixing and settling section 3, the heavy phase exits vialine 28.

A two-stage multistage countercurrent liquid-liquid extractor isrepresented in FIG. 1 by mixing and settling sections 1 and 2; lines 14,16 and 18 showing the direction of extraction solvent flow; and lines20, 22 and 24 showing the direction of heavy phase flow. In a two-stagemultistage counter current liquid-liquid extractor, mixing and settlingsection 3; lines 10, 12, 26 and 28; and gap 30 are omitted. In the twostage countercurrent liquid-liquid extractor, extraction solventcomprising extracted diphosphite-containing compounds passes from theextractor through line 18, and extracted heavy phase, i.e. raffinate,passes from the extractor through line 24.

Thus, it can be seen that the multistage countercurrent liquid-liquidextractor comprises two or more stages with countercurrent flow ofextraction solvent and heavy phase. In view of the direction of flow oflight and heavy phase through the stages of extraction, it will beappreciated that the concentration of solute, e.g.,diphosphite-containing compound, is highest in both the light and heavyphases of the first stage and lowest in the light and heavy phases ofthe final stage.

FIG. 2 is a diagrammatic representation of one type of a mixing andsettling section, also referred to herein as a mixer-settler. This typeof mixer-settler may be used in any of the stages shown in FIG. 1. Thismixer-settler comprises a mixing section 40 and a settling section 50.The mixing section 40 and the settling section 50 are separate. All ofthe effluent from the mixing section 40 flows into the settling section50. Fluid from the mixing section 40 flows through the settling section50 in a in a horizontal manner, although there is also no restriction ofmovement of fluids vertically throughout the settling section 50.

An extraction solvent is introduced into the mixing section 40 by line42. A feed comprising diphosphite-containing compounds is introducedinto the mixing section 40 by line 44. Alternatively, the contents oflines 42 and 44 may be combined upstream of the mixing section 40 andintroduced into mixing section 40 through a single inlet. These twofeeds are mixed in the mixing section 40 to provide a mixed phasecomprising an emulsion phase represented in FIG. 2 by shaded area 46.

Line 48 represents the flow of mixed phase 46 from the mixing section 40into the settling section 50. As depicted in FIG. 2, there are threephases in the settling section 50, including a heavy phase 52, a mixedphase 54, and a light phase 56. The heavy phase 52 is depleted indiphosphite-containing compounds, insofar as it has a lowerconcentration of diphosphite-containing compounds as compared with theconcentration of diphosphite-containing compounds in feed 44, due to theextraction of diphosphite-containing compounds into the light phase 56.Correspondingly, the light phase 56 is enriched indiphosphite-containing compounds, insofar as it has a higherconcentration of diphosphite-containing compounds as compared with theconcentration of diphosphite-containing compounds in extraction solventfeed 42, due to the extraction of diphosphite-containing compounds intothe light phase 56. At least a portion of the heavy phase 52 exits thesettling section 50 via line 60. At least a portion of the light phase56 is removed from the settling section 50 via line 58.

Although not shown in FIG. 2, which is diagrammatically shows the flowof fluids, it will be understood that each of the mixing section 40 andthe settling section 50 may comprise one or more stages, subsections,compartments or chambers. For example, settling section 50 may includemore than one chamber between the point of introduction of the mixedphase 46 through line 48 and the point of withdrawal of light phase andheavy phase through lines 58 and 60. Horizontal extension between thepoint of introduction of the mixed phase 46 through line 48 and thepoint of withdrawal of light and heavy phases through lines 58 and 60promotes settling of the light and heavy phases 56 and 52. The size ofthe mixed phase 54 may become progressively smaller as fluids settle andflow through the chamber. For example, the final chamber from wherefluids are removed may include little or no mixed phase 54. It willfurther be understood that mixing section 40 may include one or moretypes of mixing apparatus, such as an impeller, not shown in FIG. 2.

FIG. 3 provides a representation of another type of apparatus for use asa mixing and settling section. The type of apparatus 70 shown in FIG. 3is referred to herein as an extraction column. This extraction column 70includes a mixing section 72, a heavy phase collection section 74 and alight phase collection section 76. The entire column 70 may beconsidered to be a settling section with a mixing section betweencollection section 74 and collection section 76. In extraction column 70the mixing section 72 is part of the settling section. An extractionsolvent is introduced into column 70 through line 80. A heavier phasecomprising a diphosphite-containing compound is introduced into column70 through line 90. As the light phase passes upward through the column,and the heavy phase passes downward through the column, a mixture of thetwo phases is formed in mixing section 72. This mixture is representedin FIG. 3 as shaded mixed phase 84. This mixed phase 84 may comprise anemulsion phase. The point of introduction of heavy phase through line 90should be sufficiently above the point of introduction of the lightphase to allow for sufficient mixing of the two phases in the mixingsection resulting in the extraction of diphosphite-containing compoundsinto the light phase. The intimate mixing of light and heavy phase inmixing section 72 may be promoted by mechanical or static mixingapparatus not shown in FIG. 3. For example, mixing section 72 maycomprise baffles or perforated plates, not shown in FIG. 3.

The heavy phase 82 settles into collection section 74 and passes out ofthe column 70 through line 96. Light phase 86 settles in collectionsection 76 and passes from the column through line 92.

FIG. 4 provides a representation of a mixer-settler 100 having amultistage settling section. Mixer-settler 100 has a mixing section 110and a settling section 112. In mixer-settler 100, the mixing section 110is separate from the settling section 112. The settling section hasthree compartments, represented in FIG. 4 as sections 114, 116, and 118.These sections are separated by coalescence plates 120. The coalescenceplates 120 may be designed to provide flow of separated light and heavyphases between chambers, while restricting the flow of emulsion phasebetween chambers. A feed comprising a diphosphite-containing compound ispassed into the mixing section 110 via line 130. The extraction solventis introduced into mixing section 110 via line 132. The mixing section110 includes an impeller 134 mounted on shaft 136 to provide formechanical mixing of fluids. Mixing of the feeds provides a mixed phasecomprising an emulsion phase represented in FIG. 4 by shading 140.

The mixed phase 140 flows into the settling section 112 as an overflowfrom the mixing section 110. This mixed phase 140 is prevented fromflowing directly into the light phase 144 by baffle plate 142. Assettling occurs in settling section 112, the volume of the mixed phase140 decreases, the volume of the light phase 144 increases, and thevolume of the heavy phase 146 increases. Heavy phase 146 is removed fromsettling section 112, in particular from chamber 118, via line 152 andlight phase 144 is removed from settling section 112, in particular,from chamber 118, via line 150.

It is desirable for both a mononitrile and a dinitrile to be present inthe countercurrent contactor. For a discussion of the role ofmonodentate and bidentate ligand in extraction of hydrocyanation reactoreffluent streams, see U.S. Pat. No. 3,773,809 to Walter and U.S. Pat.No. 6,936,171 to Jackson and McKinney.

For the process disclosed herein, suitable molar ratios of mononitrileto dinitrile components include 0.01 to 2.5, for example, 0.01 to 1.5,for example 0.65 to 1.5.

Maximum temperature is limited by the volatility of the hydrocarbonsolvent utilized, but recovery generally improves as the temperature isincreased. Examples of suitable operating ranges are 40° C. to 100° C.and 50° C. to 80° C.

The controlled addition of monophosphite ligands may enhance settling.Examples of monophosphite ligands that may be useful as additivesinclude those disclosed in Drinkard et al U.S. Pat. No. 3,496,215, U.S.Pat. No. 3,496,217, U.S. Pat. No. 3,496,218, U.S. Pat. No. 5,543,536,and published PCT Application WO 01/36429 (BASF).

As described herein, the addition of Lewis base compounds to a mixturecomprising diphosphite-containing compounds, organic mononitriles andorganic dinitriles enhances settling, especially when the mixturecomprises a Lewis acid, such as ZnCl₂. Examples of suitable weak Lewisbase compounds include water and alcohols. Suitable stronger Lewis basecompounds include hexamethylene diamine, dimers and trimers ofhexamethylene diamine, ammonia, aryl- or alkyl amines, such as pyridineor triethylamine, or basic resins such as Amberlyst 21®, a commerciallyavailable basic resin made by Rohm and Haas. The addition of Lewis basemay reduce or eliminate any inhibiting effect of Lewis acid on catalystrecovery.

The reaction product of Lewis acid with Lewis base may become entrainedin the raffinate phase as it moves through the multistage countercurrentliquid-liquid extractor. In particular, this product may form aprecipitate in the raffinate phase in the form of a complex of Lewisacid with Lewis base. However, this precipitate may exist as adispersion of fine particles distributed throughout the raffinate phase.This precipitate may be removed by conventional techniques, such asfiltration, centrifugation or distillation accompanied by removal ofbottoms containing the precipitate, after the raffinate is removed fromthe last stage of the multistage countercurrent liquid-liquid extractor.

The diphosphite-containing compounds extracted by the processesdescribed herein comprise bidentate phosphorus-containing ligands. Theseextracted ligands comprise free ligands (e.g., those which are notcomplexed to a metal, such as nickel) and those which are complexed to ametal, such as nickel. Accordingly, it will be understood thatextraction processes described herein are useful for recoveringdiphosphite-containing compounds which are metal/ligand complexes, suchas a complex of zero valent nickel with at least one ligand comprising abidentate-phosphorus containing ligand.

Suitable ligands for extraction are bidentate phosphorous-containingligands selected from the group consisting of bidentate phosphites, andbidentate phosphinites. Preferred ligands are bidentate phosphiteligands.

Diphosphite Ligands

Examples of bidentate phosphite ligands useful in the invention includethose having the following structural formulae:

andwherein in I, II and III, R¹ is phenyl, unsubstituted or substitutedwith one or more C₁ to C₁₂ alkyl or C₁ to C₁₂ alkoxy groups; ornaphthyl, unsubstituted or substituted with one or more C₁ to C₁₂ alkylor C₁ to C₁₂ alkoxy groups; and Z and Z¹ are independently selected fromthe group consisting of structural formulae IV, V, VI, VII, and VIII:

and wherein

R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, and R⁹ are independently selected from thegroup consisting of H, C₁ to C₁₂ alkyl, and C₁ to O₁₂ alkoxy;

X is O, S, or CH(R¹⁰);

R¹⁰ is H or C₁ to C₁₂ alkyl;

and wherein

R¹¹ and R¹² are independently selected from the group consisting of H,C₁ to C₁₂ alkyl, and C₁ to C₁₂ alkoxy; and CO₂R¹³,

R¹³ is C₁ to C₁₂ alkyl or C₆ to C₁₀ aryl, unsubstituted or substituted.with C₁ to C₄ alkyl;

Y is O, S, or CH(R¹⁴);

R¹⁴ is H or C₁ to C₁₂ alkyl;

wherein

R¹⁵ is selected from the group consisting of H, C₁ to C₁₂ alkyl, and C₁to C₁₂ alkoxy and CO₂R¹⁶;

R¹⁶ is C₁ to C₁₂ alkyl or C₆ to C₁₀ aryl, unsubstituted or substitutedwith C₁ to C₄ alkyl.

In the structural formulae I through VIII, the C₁ to C₁₂ alkyl, and C₁to C₁₂ alkoxy groups may be straight chain or branched.

Another example of a formula of a bidentate phosphite ligand that isuseful in the present process is that having the Formula X, shown below

Further examples of bidentate phosphite ligands that are useful in thepresent process include those having the Formulae XI to XIV, shown belowwherein for each formula, R¹⁷ is selected from the group consisting ofmethyl, ethyl or isopropyl, and R¹⁸ and R¹⁹ are independently selectedfrom H or methyl:

Additional examples of bidentate phosphite ligands that are useful inthe present process include a ligand selected from a member of the grouprepresented by Formulae XV and XVI, in which all like referencecharacters have the same meaning, except as further explicitly limited:

wherein

R⁴¹ and R⁴⁵ are independently selected from the group consisting of C₁to C₅ hydrocarbyl, and each of R⁴², R⁴³, R⁴⁴, R⁴⁶, R⁴⁷ and R⁴⁸ isindependently selected from the group consisting of H and C₁ to C₄hydrocarbyl.

For example, the bidentate phosphite ligand can be selected from amember of the group represented by Formula XV and Formula XVI, wherein

R⁴¹ is methyl, ethyl, isopropyl or cyclopentyl;

R⁴² is H or methyl;

R⁴³ is H or a C₁ to C₄ hydrocarbyl;

R⁴⁴ is H or methyl;

R⁴⁵ is methyl, ethyl or isopropyl; and

R⁴⁶, R⁴⁷ and R⁴⁸ are independently selected from the group consisting ofH and C₁ to C₄ hydrocarbyl.

As additional examples, the bidentate phosphite ligand can be selectedfrom a member of the group represented by Formula XV, wherein

R⁴¹, R⁴⁴, and R⁴⁵ are methyl;

R⁴², R⁴⁶, R⁴⁷ and R⁴⁸ are H; and

R⁴³ is a C₁ to C₄ hydrocarbyl;

or

R⁴¹ is isopropyl;

R⁴² is H;

R⁴³ is a C₁ to C₄ hydrocarbyl;

R⁴⁴ is H or methyl;

R⁴⁵ is methyl or ethyl;

R⁴⁶ and R⁴⁸ are H or methyl; and

R⁴⁷ is H, methyl or tertiary-butyl;

or the bidentate phosphite ligand can be selected from a member of thegroup represented by Formula XVI, wherein

R⁴¹ is isopropyl or cyclopentyl;

R⁴⁵ is methyl or isopropyl; and

R⁴⁶, R⁴⁷, and R⁴⁸ are H.

As yet another example, the bidentate phosphite ligand may berepresented by Formula XV, wherein R⁴¹ is isopropyl; R⁴², R⁴⁶, and R⁴⁸are H; and R⁴³, R⁴⁴, R⁴⁵, and R⁴⁷ are methyl.

It will be recognized that Formulae X to XVI are two-dimensionalrepresentations of three-dimensional molecules and that rotation aboutchemical bonds can occur in the molecules to give configurationsdiffering from those shown. For example, rotation about thecarbon-carbon bond between the 2- and 2′-positions of the biphenyl,octahydrobinaphthyl, and or binaphthyl bridging groups of Formulae X toXVI, respectively, can bring the two phosphorus atoms of each Formula incloser proximity to one another and can allow the phosphite ligand tobind to nickel in a bidentate fashion. The term “bidentate” is wellknown in the art and means both phosphorus atoms of the ligand arebonded to a single nickel atom.

Further examples of bidentate phosphite ligands that are useful in thepresent process include those having the formulae XX to LIII, shownbelow wherein for each formula, R¹⁷ is selected from the groupconsisting of methyl, ethyl or isopropyl, and R¹⁸ and R¹⁹ areindependently selected from H or methyl:

Additional suitable bidentate phosphites are of the type disclosed inU.S. Pat. Nos. 5,512,695; 5,512,696; 5,663,369; 5,688,986; 5,723,641;5,847,101; 5,959,135; 6,120,700; 6,171,996; 6,171,997; 6,399,534; thedisclosures of which are incorporated herein by reference. Suitablebidentate phosphinites are of the type disclosed in U.S. Pat. Nos.5,523,453 and 5,693,843, the disclosures of which are incorporatedherein by reference.

Extraction Solvent

Suitable hydrocarbon extraction solvents include paraffins andcycloparaffins (aliphatic and alicyclic hydrocarbons) having a boilingpoint in the range of about 30° C. to about 135° C., includingn-pentane, n-hexane, n-heptane and n-octane, as well as thecorresponding branched chain paraffinic hydrocarbons having a boilingpoint within the range specified. Useful alicyclic hydrocarbons includecyclopentane, cyclohexane and cycloheptane, as well as alkyl substitutedalicyclic hydrocarbons having a boiling point within the specifiedrange. Mixtures of hydrocarbons may also be used, such as, for example,mixtures of the hydrocarbons noted above or commercial heptane whichcontains a number of hydrocarbons in addition to n-heptane. Cyclohexaneis the preferred extraction solvent.

The lighter (hydrocarbon) phase recovered from the multistagecountercurrent liquid-liquid extractor is directed to suitable equipmentto recover catalyst, reactants, etc. for recycle to the hydrocyanation,while the heavier (lower) phase containing dinitriles recovered from themultistage countercurrent liquid-liquid extractor is directed to productrecovery after removal of any solids, which may accumulate in theheavier phase. These solids may contain valuable components which mayalso be recovered, e.g., by the process set forth in U.S. Pat. No.4,082,811.

EXAMPLES

In the following examples, values for extraction coefficient are theratio of weight fraction of catalyst in the extract phase (hydrocarbonphase) versus the weight fraction of catalyst in the raffinate phase(organonitrile phase). An increase in extraction coefficient results ingreater efficiency in recovering catalyst. As used herein, the terms,light phase, extract phase and hydrocarbon phase, are synonymous. Also,as used herein, the terms, heavy phase, organonitrile phase andraffinate phase, are synonymous.

Analysis of the extract and the raffinate streams of the catalystextraction was conducted on an Agilent 1100 series HPLC and via ICP. TheHPLC was used to determine the extraction efficiency of the process.

Example 1

To a 50 mL, jacketed, glass laboratory extractor, equipped with amagnetic stirbar, digital stir-plate, and maintained at 65° C., wascharged 10 grams of the product of a pentenenitrile-hydrocyanationreaction, and 10 grams of the extract from the second stage of amixer-settler cascade, operated in counter-current flow. This extractfrom the second stage comprised approximately 50 ppm nickel and 3100 ppmdiphosphite ligand. The hexamethylene diamine concentration in thesystem was 0 ppm.

The reactor product was approximately:

85% by weight C₆ dinitriles

14% by weight C₅ mononitriles

1% by weight catalyst components

200 ppm by weight active nickel

230 ppm by weight zinc.

The laboratory reactor was then mixed at 500 rotations-per-minute, for10 minutes, and then allowed to settle for 1 minute. After settling for1 minute, a stable emulsion was present throughout the extract phase.Samples were obtained of the extract and raffinate phases of theextractor and analyzed to determine the extent of catalyst extraction.The ratio of active nickel present in the extract phase vs. theraffinate phase was found to be 5. The concentration of zinc in theraffinate was found to be 230 ppm.

Example 2

Example 1 was repeated except that hexamethylene diamine (HMD) was addedto the system. In particular, a sufficient amount of HMD was added sothat the molar ratio of Zn/HMD was 12 in the system.

Example 3

Example 1 was repeated except that hexamethylene diamine (HMD) was addedto the system. In particular, a sufficient amount of HMD was added sothat the molar ratio of Zn/HMD was 6 in the system.

Example 4

Example 1 was repeated except that hexamethylene diamine (HMD) was addedto the system. In particular, a sufficient amount of HMD was added sothat the molar ratio of Zn/HMD was 2.4 in the system.

Example 5

Example 1 was repeated except that hexamethylene diamine (HMD) was addedto the system. In particular, a sufficient amount of HMD was added sothat the molar ratio of Zn/HMD was 1.2 in the system.

Example 6

Example 1 was repeated except that bis-hexamethylene triamine (BHMT) wasadded to the system. In particular, a sufficient amount of BHMT wasadded so that the molar ratio of Zn/BMHT was 5.9 in the system.

Example 7

Example 1 was repeated except that bis-hexamethylene triamine (BHMT) wasadded to the system. In particular, a sufficient amount of BHMT wasadded so that the molar ratio of Zn/BMHT was 2.9 in the system.

Example 8

Example 1 was repeated except that bis-hexamethylene triamine (BHMT) wasadded to the system. In particular, a sufficient amount of BHMT wasadded so that the molar ratio of Zn/BMHT was 1.2 in the system.

Example 9

Example 1 was repeated except that bis-hexamethylene triamine (BHMT) wasadded to the system. In particular, a sufficient amount of BHMT wasadded so that the molar ratio of Zn/BMHT was 12 in the system.

Example 10

Example 1 was repeated except that 1,2-dicyclohexylamine (DCH) was addedto the system. In particular, a sufficient amount of BHMT was added sothat the molar ratio of Zn/DCH was 1.6 in the system.

Example 11

Example 1 was repeated except that 1,2-dicyclohexylamine (DCH) was addedto the system. In particular, a sufficient amount of BHMT was added sothat the molar ratio of Zn/DCH was 2 in the system.

Example 12

Example 1 was repeated except that 1,2-dicyclohexylamine (DCH) was addedto the system. In particular, a sufficient amount of BHMT was added sothat the molar ratio of Zn/DCH was 4 in the system.

Example 13

Example 1 was repeated except that 1,2-dicyclohexylamine (DCH) was addedto the system. In particular, a sufficient amount of BHMT was added sothat the molar ratio of Zn/DCH was 8 in the system.

Example 14

Example 1 was repeated except that triethylamine (TEA) was added to thesystem. In particular, a sufficient amount of BHMT was added so that themolar ratio of Zn/TEA was 1 in the system.

Example 15

Example 1 was repeated except that octylamine was added to the system.In particular, a sufficient amount of BHMT was added so that the molarratio of Zn/octylamine was 1.3 in the system.

Comparative Example 16

Example 1 was repeated except that polyethyleneglycol (PEG-600) wasadded to the system. In particular, a sufficient amount of PEG-600 wasadded so that the molar ratio of Zn/PEG-600 was 1.5 in the system.

Comparative Example 17

Example 1 was repeated except that adipamide was added to the system. Inparticular, a sufficient amount of adipamide was added so that the molarratio of Zn/adipamide was 2.3 in the system.

Comparative Example 18

Example 1 was repeated except that triphenyl phosphine (Ph₃P) was addedto the system. In particular, a sufficient amount of Ph₃P was added sothat the molar ratio of Zn/Ph₃P was 1 in the system.

Example 19

Example 1 was repeated except that calcium hydroxide (Ca(OH)₂) was addedto the system. In particular, a sufficient amount of Ca(OH)₂ was addedso that the molar ratio of Zn/Ca(OH)₂ was 0.3 in the system.

Results of Examples 1-19 are summarized in Table 1.

TABLE 1 Ex./ Temp Time Zn/ Zn/ CEx. (° C.) (min) Additive Additive KLLNi 1 65 10 None 5 1.15 2 65 10 12.0 HMD 13 1.09 3 65 10 6.0 HMD 13 1.114 65 10 2.4 HMD 23 0.43 5 65 10 1.2 HMD 84 0.12 6 65 10 5.9 BHMT 1020.12 7 65 10 2.9 BHMT 80 0.17 8 65 10 1.2 BHMT 112 0.17 9 65 10 12.0BHMT 18 10 65 10 1.6 DCH 119 0.85 11 65 10 2 DCH 114 12 65 10 4 DCH 271.03 13 65 10 8 DCH 8 1.05 14 65 10 1 TEA 20 0.94 15 65 10 1.3Octylamine 63 0.96 16 65 10 1.5 PEG-600 5 1.07 17 65 10 2.3 Adipamide 618 65 10 1 Ph₃P 4 1.15 19 65 10 0.3 Ca(OH)₂ 14 KLL = amount of catalystin the extract/amount of catalyst in the raffinate; Zn/Additive = themolar ratio of the zinc-to-additive during extraction; Zn/Ni = the ratioof the total amount of zinc-to-nickel remaining in both phases after theextraction, as determined by inductively coupled plasma spectrometry(ICP).

The data summarized in Table 1 represent evaluations of a number ofmaterials as potential additives for improved catalyst extraction.Examples 1-5 show the beneficial effect of hexamethylene diamine (HMD)on catalyst extraction, as the HMD loading increases (represented bydecreasing Zn/Additive ratio) the catalyst extraction efficiency(represented by KLL) increases. Examples 6-9 show the beneficial effectof bis-hexamethylene triamine (BHMT) on catalyst extraction. Examples10-13 show the beneficial effect of triethylamine (TEA) on catalystextraction. Example 15 shows the beneficial effect of adding octylamineon catalyst extraction. Example 19 shows the beneficial effect ofcalcium hydroxide on catalyst extraction. By way of contrast,Comparative Examples 16-18 show little effect on catalyst extractionusing PEG-600, adipamide, and triphenyl phosphine, respectively.

Examples 20-25

These Examples 20-25 illustrate that effective catalyst recovery occursfor a mononitrile to dinitrile ratio greater than 0.65.

Five different mixtures comprised of a Ni diphosphite complex, with thediphosphite ligand shown in Structure XX (where R¹⁷ is isopropyl, R¹⁸ isH, and R¹⁹ is methyl), ZnCl₂ (equimolar with Ni) and differing in theratio of mononitrile to dinitrile, were separately liquid-liquid batchextracted with an equal weight of cyane (i.e. cyclohexane). The molarratio of organic mononitrile to organic dinitrile and the resultingextraction coefficients are shown in the Table 2 below. A compound maybe effectively recovered if it has an extraction coefficient of 1 orgreater at solvent to feed ratios greater than 1 using a countercurrentmultistage extractor.

TABLE 2 Catalyst and ligand extraction coefficients for varying ratiosof mononitriles-to-dinitriles Catalyst extraction Ligand extractionExample mononitrile/dinitrile coefficient coefficient 1 2.33 1.28 4.09 21.85 1.33 8.08 3 1.19 2.02 16.97 4 0.91 2.63 35.99 5 0.57 4.82 49.59

Example 26

This Example demonstrates the effect of hold-up time on theextractability of the diphosphite ligand catalyst.

A mixture comprised predominantly of organic dinitriles and a Nidiphosphite complex, the structure of the diphosphite ligand being shownin Structure XX (where R¹⁷ is isopropyl, R¹⁸ is H, and R¹⁸ is methyl)and ZnCl₂ (equimolar with Ni) was divided into two portions. Bothportions are liquid-liquid extracted in a three-stage contactor at 40°C., with an equal weight of cyclohexane. Both portions were sampled withtime and the progress of the catalyst recovery into the extract phase isshown in Table 3 as the percent of the final steady state value achievedat a given time.

TABLE 3 Concentration of Diphosphite ligand with time in the extractingsolvent phase. Time, % of steady state minutes concentration at 40° C. 212 4 19 8 34 14 52 30 78 60 100 91 100

Example 27

This Example illustrates the effect of temperature on the extractabilityof catalyst with first-stage extraction solvent recycle.

A mixture comprised predominantly of organic dinitriles and a Nidiphosphite complex, the structure of the diphosphite ligand being shownin Structure XXIV (where R¹⁷ is methyl, R¹⁸ is methyl and R¹⁹ is H) andZnCl₂ (equimolar with Ni) was divided into three portions. The portionswere batch liquid-liquid extracted at 50° C., 65° C. and 80° C.,respectively, with an equal weight of n-octane and monitored with time.The results are shown in Table 4.

TABLE 4 % of steady state % of steady state at % of steady state at Timeat 50° C. 65° C. 80° C. 2 0.0 0.0 1.8 4 0.0 0.0 1.6 8 0.0 0.0 3.6 14 0.00.0 4.3 20 0.0 0.0 3.6 30 0.0 0.0 7.6 60 0.0 1.6 16.3 90 0.7 4.0 48.6

Example 28

This Example demonstrates the effect of adding water in three-stageextraction with cyclohexane recycle in the last stage.

Fifteen grams of a mixture comprised predominantly of organic dinitrilesand a Ni diphosphite complex, the structure of the diphosphite ligandbeing shown in Structure XXIV (where R¹⁷ is methyl, R¹⁸ is methyl andR¹⁹ is H) and ZnCl₂ (equimolar with Ni), was extracted in a three-stagecontinuous extractor at a temperature of 50° C. with an equal weight ofcyclohexane for one hour resulting in an catalyst extraction coefficientof 4.3, as measured by the amount of catalyst in the extract of thefirst stage divided by the amount of catalyst in the feed of thereaction mixture fed to the last stage of the three-stage countercurrentextractor.

To this mixture, 100 microliters of water was added. After continuing toheat and agitate for another hour, the diphosphite Ni extractioncoefficient was measured as 13.4—a threefold increase.

Examples 29 and 30

These Examples demonstrate the effect of adding hexamethylene diamine(HMD) to the extraction zone.

Example 1 was repeated except that hexamethylene diamine was added tothe product of a pentene-hydrocyanation reaction. To a 50 mL, jacketed,glass laboratory extractor, equipped with a magnetic stirbar, digitalstir-plate, and maintained at 65° C., was charged 10 grams of theproduct of pentene-hydrocyanation reactor product, and 10 grams of theextract from the second stage of a mixer-settler cascade, operated incounter-current flow.

The reactor product was approximately:

85% by weight C₆ dinitriles

14% by weight C₅ mononitriles

1% by weight catalyst components

360 ppm by weight active nickel.

The laboratory reactor was then mixed at 1160 rotations-per-minute, for20 minutes, and then allowed to settle for 15 minutes. A stable emulsionwas present throughout the extract phase in the absence of the additionof HMD. After 15 minutes of settling, essentially no emulsion phase waspresent when HMD was added. Samples were obtained of the extract andraffinate phases of the extractor and analyzed to determine the extentof catalyst extraction.

TABLE 5 Effect of hexamethylene diamine on catalyst extractionConcentration of HMD added Catalyst Example (ppm) recovery (KLL) Stableemulsion 1 0 14 Yes 29 250 43 No 30 500 80 No

Examples 31-36

These Examples demonstrate the beneficial effect of adding hexamethylenediamine (HMD) on the reaction temperature required for catalystextraction. For Examples 31-33, Example 1 was repeated, but the mixingtime was 20 minutes, and the temperature was varied as indicated inTable 6. For Examples 34-36, Example 5 was repeated, and the temperaturewas varied as indicated in Table 6.

TABLE 6 Effect of hexamethylene diamine on temperature for catalystextraction. Temp Example (° C.) KLL Zn/HMD 31 65 16.76 No HMD 32 5513.25 No HMD 33 45 8.06 No HMD 34 65 84.42 1.2 35 55 82.91 1.2 36 4582.00 1.2

The data summarized in Table 6 represent evaluations of catalystextraction performed at varying temperature from 45 to 65 degreesCelsius, with and without HMD present. Examples 31-33 show that catalystextraction increases linearly with increasing temperature (representedby KLL). Examples 34-36 show that catalyst extraction does not requireincreased temperature when HMD added.

Examples 37-44

These Examples demonstrate the beneficial effect of adding hexamethylenediamine (HMD) on the mixing time required for catalyst extraction. ForExamples 37-40, Example 31 was repeated, and the mixing time was variedas indicated in Table 7. For Examples 41-44, Example 5 was repeated, andthe mixing time was varied as indicated in Table 7.

TABLE 7 Effect of hexamethylene diamine on mixing time required forcatalyst extraction. Example Mixing Time KLL Zn/HMD 37 20 16.13 No HMD38 10 14.86 No HMD 39 5 14.49 No HMD 40 1 11.05 No HMD 41 10 84.42 1.242 5 114.34 1.2 43 1 98.24 1.2 44 0.5 56.23 1.2

The data summarized in Table 7 represent evaluations of catalystextraction performed at varying mixing time from 20 minutes to 30seconds, with and without HMD present. Examples 37-40 show that adecrease in catalyst extraction occurs when the mixing time is decreasedto less than 5 minutes. Examples 41-44 show that catalyst extractiondoes not decrease until the mixing time is decreased to less than 1minute, when HMD added.

1. A process for recovering diphosphite-containing compounds from a feedmixture comprising diphosphite-containing compounds, organicmononitriles, organic dinitriles and a Lewis acid in a multistagecountercurrent liquid-liquid extractor with extraction solventcomprising aliphatic hydrocarbon, cycloaliphatic hydrocarbon or amixture of aliphatic and cycloaliphatic hydrocarbon, said processcomprising: a) flowing the feed mixture to the first stage of themultistage countercurrent liquid-liquid extractor; and b) contacting thefeed mixture with extraction solvent in the multistage countercurrentliquid-liquid extractor, wherein the first stage of the multistagecountercurrent liquid-liquid extractor comprises a mixing section and asettling section, wherein the mixing section provides a mixed phasecomprising a light phase and a heavy phase, wherein a light phaseseparates from a heavy phase in the settling section, wherein a Lewisbase is added to the mixing section of the first stage of the multistagecountercurrent liquid-liquid extractor, wherein the light phasecomprises extraction solvent and extracted diphosphite-containingcompounds, wherein the heavy phase comprises organic mononitriles,organic dinitriles and a complex of said Lewis acid and said Lewis base,wherein at least a portion of the light phase is withdrawn from thesettling section and treated to recover diphosphite-containing compoundsextracted into the light phase, wherein at least a portion of the heavyphase is passed to the second stage of the multistage countercurrentliquid-liquid extractor, and wherein the Lewis base is selected from thegroup consisting of polyamines.
 2. The process of claim 1, wherein theaddition of Lewis base to the mixing section of the first stage of themultistage countercurrent liquid-liquid extractor is sufficient toresult in enhanced settling of the light phase and heavy phase in thesettling section of the first stage.
 3. The process of claim 1, whereinthe addition of Lewis base to the mixing section of the first stage ofthe multistage countercurrent liquid-liquid extractor is sufficient toachieve at least one of the following results: (a) a reduction in thesize of an emulsion phase in the settling section, based upon the sizeof the emulsion phase in the absence of recycle of the heavy phase; (b)an increase in the rate of settling in the settling section, based uponthe rate of settling in the absence of recycle of the heavy phase; (c)an increase in the amount of diphosphite-containing compounds in thelight phase, based upon the upon the amount of diphosphite-containingcompounds in the light phase in the absence of recycle of the heavyphase; (d) a reduction in the size of a rag layer in the settlingsection, based upon the size of a rag layer in the settling section inthe absence of recycle of the heavy phase; and (e) reduction in the rateof formation of a rag layer in the settling section, based upon the rateof formation of a rag layer in the settling section in the absence ofrecycle of the heavy phase.
 4. The process of claim 1, wherein theaddition of Lewis base to the mixing settling section of the first stageis sufficient to result in improved extraction of diphosphite-containingcompounds based upon the extraction of diphosphite compounds in theabsence of recycle of addition of Lewis base.
 5. The process of claim 1,wherein the addition of Lewis base to the mixing settling section of thefirst stage is sufficient to result in improved extraction ofdiphosphite-containing compounds based upon the extraction ofdiphosphite compounds in the absence of recycle of addition of Lewisbase, at reduced temperature.
 6. The process of claim 1, wherein theaddition of Lewis base to the mixing settling section of the first stageis sufficient to result in improved extraction of diphosphite-containingcompounds based upon the extraction of diphosphite compounds in theabsence of recycle of addition of Lewis base, with reduced mixing time.7. The process of claim 1, wherein the Lewis base is cofed to the mixingsection along with the feed mixture comprising diphosphite-containingcompounds, organic mononitriles, organic dinitriles and Lewis acid. 8.The process of claim 1, wherein the Lewis base is separately fed to themixing section apart from the feed mixture comprisingdiphosphite-containing compounds, organic mononitriles, organicdinitriles and Lewis acid.
 9. The process of claim 1, wherein the Lewisacid is ZnCl₂.
 10. The process of claim 1, wherein the extractionsolvent feed from the second stage comprises at least 1000 ppm ofdiphosphite-containing compounds.
 11. A process according to claim 1wherein the diphosphite-containing compound is a Ni complex with adiphosphite ligand selected from the group consisting of:

and wherein in I, II and III, R¹ is phenyl, unsubstituted or substitutedwith one or more C₁ to C₁₂ alkyl or C₁ to C₁₂ alkoxy groups; ornaphthyl, unsubstituted or substituted with one or more C₁ to C₁₂ alkylor C₁ to C₁₂ alkoxy groups; and wherein Z and Z¹ are independentlyselected from the group consisting of structural formulae IV, V, VI,VII, and VIII:

and wherein R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, and R⁹ are independentlyselected from the group consisting of H, C₁ to C₁₂ alkyl, and C₁ to C₁₂alkoxy; X is O, S, or CH(R¹⁰); R¹⁰ is H or C₁ to C₁₂ alkyl;

and wherein R¹¹ and R¹² are independently selected from the groupconsisting of H, C₁ to C₁₂ alkyl, and C₁ to C₁₂ alkoxy and CO₂R¹³, R¹³is C₁ to C₁₂ alkyl, or C₆ to C₁₀ aryl unsubstituted or substituted withC₁ to C₄ alkyl; Y is O, S, or CH(R¹⁴); R¹⁴ is H or C₁ to C₁₂ alkyl;

wherein R¹⁵ is selected from the group consisting of H, C₁ to C₁₂ alkyl,and C₁ to C₁₂ alkoxy and CO₂R¹⁶, R¹⁶ is C₁ to C₁₂ alkyl, or C₆ toC₁₀aryl, unsubstituted or substituted with C₁ to C₄ alkyl, and whereinfor structural formulae I through VIII, the C₁ to C₁₂ alkyl, and C₁ toC₁₂ alkoxy groups may be straight chain or branched.
 12. The process ofclaim 9, wherein at least a portion of the diphosphite-containingcompound is complexed with zero valent Ni.
 13. The process of claim 1wherein at least one stage of the extraction is carried out above 40° C.14. (canceled)
 15. (canceled)
 16. The process of claim 13 wherein thepolyamine comprises at least one selected from hexamethylene diamine anddimers and trimers of hexamethylene diamine.
 17. The process of claim 13wherein the polyamine comprises bis-hexamethylenetriamine. 18.(canceled)
 19. The process of claim 1 wherein the extraction solvent iscyclohexane.
 20. The process of claim 1 wherein the feed mixture is aneffluent stream from a hydrocyanation process.
 21. The process of claim20 wherein the hydrocyanation process includes a 3-pentenenitrilehydrocyanation process.
 22. The process of claim 20 wherein thehydrocyanation process includes a 1,3-butadiene hydrocyanation process.23. The process of claim 1, wherein the first stage of the multistagecountercurrent liquid-liquid extractor takes place in an extractioncolumn, wherein the entire column is a settling section comprising amixing section between a heavy phase collection section and a lightphase collection section, and wherein the Lewis base is added to themixing section.
 24. The process of claim 1, wherein the first stage ofthe multistage countercurrent liquid-liquid extractor takes place in anmixer-settler, wherein the mixer-settler comprises a settling sectionwhich is separate from the mixing section, and wherein the Lewis base isadded to the mixing section.